Systems for occupant detection and classification in cars are known.
In addition, radar-based seat belt reminder sensors and the use of the “R-Value” concept are known. Detectors that act as monitors for (sleeping) babies in their rooms are also available.
Techniques for detection of humans in vehicles based on breathing detection have been described previously. For example, U.S. Pat. No. 6,753,780 discloses motion sensing system and method for detecting an occupant in a vehicle with sensitivity to detect small movement, such as movement caused by heartbeat and breathing. A radar motion sensor located in a compartment of the vehicle transmits and receives signals and generates sensed signals. A controller converts the sensed signals to a frequency domain. The controller further processes the frequency domain of sensed signals and determines the presence of movement of an occupant due to one of heartbeat and breathing of the occupant.
U.S. Pat. No. 7,036,390 discloses an in-vehicle body detection method in which a synthetic wave is obtained which represents the synthesis of a transmitted wave radiated from a sensor and a reflected wave returned from a breathing human body, and the presence or absence of a human in the vehicle is detected from the envelope of the synthetic wave. When the presence of a human is detected continuously for a predetermined length of time, it is determined that a human is present in the vehicle.